1. Field of the Invention
The present invention relates to improvements in hollow charges.
Due to the evolution of armorings for an ever more effective protection of combat tanks, notably by composite assemblies composed of several layers of different materials, inert or active, there has been development aimed at increased performance of hollow charges.
2. Background of the Invention
The level reached today, in 1984, of piercing armor of 7 to 8 calibers on an armored steel target is still insufficient. The present invention proposes several improvements to hollow charges allowing reaching the objective of perforating steel armors of at least 10 calibers.
It is known by experience (checked by informatics calculations) that the vertex of a conical liner having a very closed or acute vertex angle (for example 30-35.degree. and in any case &lt;40.degree.) produces very high speeds for the head of the jet, all the more important as the vertex angle is smaller.
However, the perforation level of the hollow charge does not depend only on the speed of the jet head. To obtain the maximum efficiency of the hollow charge against armor plates, especially composite plates having inert or active layers, it is preferable that the liner be made of copper or other materials according to the invention, such as tantalum for example, and the liner should have a wider angle at the front or base thereof. Suitable profiles of the liner can be ogival or arch shaped, inflected, with multiple slopes, etc.
But on the one hand, for maintaining the jet speed within physically reasonable limits, according to the material used (this higher speed limit is of about 10,000 m/s for copper), that is for preventing the disruption of the jet formed, which would be contrary to the object in view, a dosage of the thicknesses of the wall is accomplished according to the invention as a function of the angle and of the fraction or portion of liner and of its estimated position in the jet; the result is, for the rear portion of the liner according to the invention, adapted wall thickness laws of the liner: a degressive thickness, a progressive-constant thickness, a constant-degressive thickness, etc.
On the other hand, it should be remembered that the "tail" elements of the jet have third origin at the base of the liner. The speed of such elements is between 2,000 and 4,000 m/s. The diameter of said elements is important and many of them do not take part in the penetration since any slight deviation to which they are possibly subjected during their formation directs them to the edge of the crater formed by the elements of the jet head.